Stoker



J. R. GRAVES STOKER zal Patented July 4, 1939 UNITED sTA'rEs PATENToFFIcE s'roKEa of Delaware Application August 5,

13 Claims.

This invention rel'ates to stokers of the type employing a conveyorscrew for delivering coal to a distributing device positioned atan-openng in a furnace wall.

It is the prncipal object of this invention to prolong the life of vitalstoker parts upon which coal lies in certain dormant zones duringpassage of the bulk of the coal to the distributing device, and in whichdormant zones the corrosive action of the coal causes such vital stokerparts to deteriorate rapidly.

More specifically, the invention contemplates the provision of guardplates which are in a novel I relation With the stoker conduit and vitalparts 15 of the distributing device whereby the objectionable dormantzones of coal and the attendant dificulties are eliminated.

As a further object thereof, the invention |consists in the provision ofguard plates which constitute forward extensions of a cylindricalconduit at the juncture thereof with a conduit discharge mouth which isof somewhat angular configuration in transverse cross section.

Other' objects are to provide the novel guard plates, their mode ofattachment to the distributor head and their novel relation with vitalstoker parts.

In the drawing:

Fig; 1 is a Vertical longitudinal section through the delivery end of astoker and the adjacent portion of a furnace showing the invention asapplied thereto;

Figs. 2, 3 and 4 are views in section taken along the lines 2 2, 3-3,and 4-4, respectively, of Fig. 1; and A Fig. 5 is a fragmentary viewsimilar to Fig. 4, illustrating a modification.

Referring `to the drawing, there is shown at a portion of an upstandingwall of a boiler firebox 8 having a firing opening 1| therein to whichfuel is advanced by the conveyor screw 12. The screw 12 is housed withinthe inclined stoker conduit 13 which opens endwise into the firingopening I I. At its forward end the stoker conduit 13 is provided With amouth portion 14 extending across the lower portionvof the firingopening. Any preferred construction may be employed to attach theconduit 13 to the wall 111 for the purpose of maintaining the conduitmouth portion 14 in communication with the firing opening 1 I. Intransverse cross section, rearward of its mouth portion, the interior ofthe conduit 13 is circular in cross section. Immediately forward of itscircular portion, the conduit changes abruptly to an inverted U-section,and in its for- 1936, Serial No. 94,357

ward extent changes gradually to the rectangular cross section, asillustrated in Figures 4, 3 and 2. a

Forward of its circular portion, the bottom of the stoker conduit 13 isopen between the side walls 15, 16. A distributor member or head 1'1having a flat upper surface is detachably disposed, as will presentlyappear, in the opening 9 at the upper forward end of the stoker conduit13 to form a floor portion for the delivery end of the conduit. It willbe observed that 'the distributor head 11 extends beyond the conduitmouth portion into the firing opening 11 to a point intermediate theinner 'and outer surfaces of the firebox wall 10. At its forward end thedistributor head 1'1 detachably supports the table 18. a

A plurality of vertically spaced horizontal rows of jet openings 19extend across the upright face 20 of the distributor head 11. These jetopenings communicate with one or more chambers 2| formed within thedistributor head 1'1 beneath the upper surface thereof. Steam or anyother suitable pressure fiuid is supplied to the chambers 21 throughintake openings such as 22. Fuel advanced by the conveyor screw 12 ismoved over the upper surface of the distributor member 11 into the zoneof action of the pressure fluid blasts discharging from the jet openings19, which blasts serve to project the fuel across the table 18 fordistribution over the firebed in the firebox. Adjustable defiector vanes23,24 constitute forward continuations of the conduit side walls 15, 16,respectively, and they are mounted upon pivot pins such as 25 whereby-each may be set at any desired angle with respect to the upright face20 of the distributor head 11 for the purpose of controlling thedelivery of fuel to the distributing device.

The distributor head 11 is seated upon ledges 26 which extend inwardlyfrom the side walls 15, 16 and ledges 26a extending forward of the'transversely disposed boss 2'1 depending from the lower forward edge ofthe tubular portion of the stoker conduit, said side walls and boss 21defining the opening 9 in the bottom of the stoker conduit 13. Adjacentthe boss 21, each side wall 15, 16 has threaded thereinto a screw 28,the tapered inner portion 29 of which is arranged' to press firmlyagainst the upper surface of the distributor head 1'1 and also against alug such as 30 whereby upward and fore and aft movement of thedistributor head 1'1 is restrained during normal operation of thestoker. 'Whenever itis desired to remove the distributor head 1'1 fromits position over the opening 9, the screws 28are threaded outwardly adistance to clear the lugs 30,, Whereupon the mechanic may remove thehead by drawing the same forwardly and upwardly into the firebox aslightdistance. stood that the firedoor 3| is thrown open during thisloperation.

Due to the fact that the change in cross sectional configuration of thestoker conduit from its circular portion to its inverted U-shapedportion is abrupt, a certain amount 'of coal, heretofore, in passingfrom the circular section into the inverted U-shaped section, wouldremain dormant along the side walls |5, |6 of the stoker conduit |3 andalso along the lateral sides of the upper surfacev 32 of the distributorhead H. This dormant zone of coal extends a substantial disancelorwardof the circular section of the conuit It has been experienced in actualservice of the described stoker device, prior to this invention, thatthe coal lying more or. less dormant along the lateral sides of thedistributor head |'l will `cause corrosion of its surface 32.,Furthermore, since the coal along the corroded portions of' the surface32 is not subject to the direct impelling action of the'conveyor screw|2, whatever forward movement of the coal in these zones occurs isaccompanied by a sliding action of the coal lumps along the corrodedportions of the surface. The coal sliding, or'being pushed, slowlyalongthe aifected portions of the surface'32 is under greater pressure atthese zones than at other portions of the stoker conduit |3;consequently, greater friction results so -that within a comparativelyshort time the surface 32 wears 'through to van extent that,.the coredchambers -an inclined rearward surface portion 40 and a forward surfaceportion 4| at a lesser angleof inclination with respect tothe horizontalthan surface portion 40. On the outer-portions of the forward surfacepor-tion 4| areformed ridges 42 and 43 constituting prolongations -ofthe rear- 'ward surface. portion 40, the ridges'42 and 43 having planeupper surfaces in the plane of the rearward surface portion 40. Eachguard plate 33 has a plane under surface providing surface contactbetween the aforesaid under'surface of the guard-platesf33 on the onehand' and the v rearward surface portion 40 and' the surfaces of theridges 42 and 43 of the distributor. head |1 on the otherhand. Eachguard plate 33 has an arcuate-shaped wall 34, the radius of vcurvatureof which approximates that of the`circular portion of the stokerconduit. At its rearmost porltion, the upper edge 35 of leach arcuate'wall' 34 extends to a maximum above the upper surface of the surface``'32, and is inclined toward its lower edge- The .upper edge 35 of eacharcuate wall 3-4 throughoutthe' length thereof contacts the respectiveside walls |5, IG of the stoker conduit.-

The guard plate may be constructed, if desired, with the arcuate walls34 thereof joined at their It will be under-v ,Thisinner portions, or,as shown in Fig. 5, these arcuate walls 34a may be made integral withthe upper surface 32a of the distributor head I'Ia. However, it ispreferred that ythe arcuate walls 34 at the sides of the stoker conduit|3 be mader 5 v separable from`each other in order to facilitate theirapplication tol` the distributor head l'l.

As illustrated in Figures 3 and v4=, each guard plate 33 is provided atits under side with an enlarged portion such as 36 into each of which afscrew 31 is threaded. Each screw 31 passes through the upper surface 32of the distributor head |1 and detachably secures each guard plate tothe distributor head ll. Before securing the guard plates 33 to thedistributor head l'l, the former are'each fitted into the stoker conduit|3 and their Vpositions carefully scribed .upon the 'upper surface 32.

Whereupon, the distributor head |.1 is removed form the stoker conduitin the heretofore described manne'r, the guard plates 33 placed upontheir scribedroutlines and holes drilled in the distributor' head I'land tapped in the guard plates 33 whereby the screws 31 are passedthrough the head" and threaded into the guard plates for ,securing theylatter to the former. V

From the foregoing, it will be apparent that the herein describediconstruction prolongs the life of the distributor head I'l by insuringthat coal is moved constantly therealong because the zones where coalmay lie dormant have been effectively eliminated..

'I claim the following as new and useful:

-1. A pressure fluid distributor head for ai stoker comprising a fiatupper surfacenmeans providing ya plurality lof pressure fiuid chambers`underneath said upper surface; a wall depending from one end ofsaidupper surface and having a plurality 'of pressurefluid dischargeorifices therein communicating with said chambers,'and an arcuate wallat each side of said upper surface extending upwardly therefrom, saidarcuate -walls extending forwardly from the end of said upper surfaceremote from the said depending wall and being spaced inwardly from theside edges o f said upper surface at the last named end thereof anddiverging to the side edges of saidupper -surface at they extendforwardly.

2. A pressure fluid distributor head' for a Vstoker' comprising a flat'upper surface, means providing a plurality of pressure fluid chambersunder-neath said upp'er surface, a wall depending from one end of saidupper surface and having a plurality of pressure'fiuid dischargeorifices therein communicating with said chambers,

. and an arcuate wall at each side of said upper surface formedintegrally therewith and extending upwardly therefrom, said arcuatewalls extending forwardly from the end of said upper surface remote fromsaid depending' wall and being spaced inwardly from the side edges ofsaid top surface at the last named end thereof and diverging to the sideedges of said .upper surface as they extend forwardly.

, 3. A guard plate for a stokerdistributor head comprising an' arcuatewall having the same `radius of curvature throughout its length, the

bottom of said arcuate wall throughout the length -thereof having aplane surface, said arcuate wall at one end of said guard plate being ata maximum 'distance above the aforesaid plane of said bottom surface andthence sloping to- Ward said bottom surface, said bottom surface beingprovided with threaded .openings.

. 4. In combination with a stoker conduit having a tubular portionprovided with a bottom wall. the inner surface thereof bing arcuate intransverse cross section, and a delivery portion immediately forward ofsaid tubular portion, said delivery portion including upright sidewalls, a distributor head detachably disposed in said delivery portionbetween the lower ends of said side walls and immediately forward of thetubular portion of said conduit, said distributor head including a fiatupper surface constituting, a support for coal passing through saidconduit, and an upstanding wall located within and at each side o-fsaid'delivery portion immediately forward of the tubular portion of thestoker conduit, said upstanding walls being disposed on the uppersurface of said distributor head spaced inwardly at their lower edgesfrom the side walls of said delivery portion and extending upwardly tosaid side walls. v v

5. In combination with a stoker conduit having a tubular portionprovided with a bottom wall, the inner surface thereof being arcuate intransverse cross section, and a delivery portion immediately forward ofsaid tubular portion, said de-I livery portion including upright sidewalls, a distributor head detachably disposed in said delivery portionbetween the lower ends of said side walls and immediately forward of thetubular portion of said conduit, said distributor head including a fiatupper surface constituting a support for coal passing through saidconduit, and an upstanding arcuate wall located Within and at each sideof said delivery portion immediately forward of the tubular portion ofthe stoker conduit, said arcuate walls being disposed on the uppersurface of said distributor head spaced inwardly at their lower edgesfrom the side walls of said delivery portion and curving upwardly andoutwardly to said side walls.

6. In combination with a stoker conduit having a tubular portionprovided with a bottom wall, the inner surface thereof being arcuate intransverse cross section, and a delivery portion immediately forward ofsaid tubular portion, said delivery portion including upright sidewalls, a distributor head detachablydisposed in said delivery portionbetween the lower ends of said side walls and immediately forward of thetubular portion of said conduit. said distributor head including a fiatupper surface constituting a support for coal passing through saidconduit, and a separable upstanding wall located within yand at eachside of said delivery portion immediately forward of the tubular portionof the stoker conduit, said f upstanding walls being detachably securedon the upper surface of said distributor head spaced inwardly at theirlower edges from` the side walls of said delivery portion and extendingupwardly to said side walls.

7. In combination with a stoker conduit having a tubular portionprovided With a bottom wall, the inner surface thereof being arcuate intransverse cross section, and a delivery portion immediately forward ofsaid tubular portion, said delivery portion including upright sidewalls, a

distributor head detachably disposed in said delivery portion betweenthe lower ends of said side Walls and immediately forward of the tubularportion of said conduit said distributor head including a fiat uppersurface constituting a support for coal passing through said conduit;and a separable arcuate upstanding wall located within and at each sideof said delivery portion immediately forward of the tubular portion ofthe stoker conduit, said arcuate walls being detachably secured on theupper surface of said distributor head spaced inwardly atfitheir loweredges from the side walls of said delivery portion and curving upwardlyand outwardly to said side walls.

8. In combination with a stoker conduit having a tubular portionprovided with a bottom wall, the inner surface thereof being arcuate intransverse cross section, and a delivery portion immediately forward ofsaid tubular portion, said delivery portion including upright sidewalls, a distributor head detachably disposed in said delivery portion'between the lower ends of said side walls and immediately forward ofthe tubular portion of said conduit, said distributor head including afiat upper surface constituting a support for coal passing through saidconduit, and an arcuate wall located within and at each side of saidldelivery portion immediately forward. of the tubular portion of thestoker conduit, said arcuate walls being integrally fcrmed with theupper surface of said-distributor head spaced inwardly at their loweredges from the side .walls of said delivery portion and curving upwardlyand outwardly to said side walls.

9. In combination with al stoker conduit having a tubular portionprovided with a bottom wall, the inner surface thereof being arcuate intransverse cross section, and a delivery portion immediately forward ofsaid tubular portion, said delivery portion including, upright sidewalls, ledges extending laterally inward of the lower ends of saidupright side walls and forward of the lower forward end of said tubularportion, a distributor head seated on said ledges between the lower endsof said side walls and immediately forward of the lower forward end ofsaid tubular portion, said distributor head including a fiat uppersurface constituting a support for coal passing through said conduit,and an upstanding wall located within and at each side of said deliveryportion immediately forward of the tubular portion of the stokerconduit, said upstanding walls being disposed on the upper surface ofsaid distributor head spaced inwardly at their lower edges from the sideWalls of said delivery portion and extending upwardly to said sidewalls.

10. In combination with a stoker conduit having a tubular portionprovided with a bottom wall, the inner surface thereof being arcuate intransverse cross section, and a delivery portion immediatelyforward ofsaid tubular portion, said delivery portion including upright sidewalls, ledges extending laterally inward of the lower ends of saidupright side walls and forward of the lower forward end of said tubularportion, a distributor head seated on said ledges between the lower endsof said side lwalls and immediately forward of the lower forward end ofsaid tubular portion, said. distributor head including a fiat uppersurface constituting a support for coal passing through said conduit,and an upstanding arcuate wall located vvithin and at each side of saiddelivery portion immediately forward of the tubular portion of thestoker conduit, said arcuate walls being disposed on the upper surfaceof said distributor headspaced inwardly at their lower edges from theside walls of said delivery portion and curving upwardly and outwardlyto said side Walls.

11. In combination With a stoker conduit having a tubular portionprovided with a bottom wall, the inner surface thereof being arcuate intranverse cross section, and a delivery portion immediately forward ofsaid tubular portion, said delivery portion including upright sidewalls; 'w

ledges 'extending laterally inward of the lower ends of said uprightside walls and forward of the lower forward end of said tubular portion,a distributor head seated on said ledges between the lower ends of saidside walls and immediately forward of the lower forward end of saidtubular 'portion,- said distributor head including a flat upper surfaceconstituting a support for coal passing through said conduit, and aseparable upstandingvwall located within and at each side of saiddelivery portion immediately for- Ward of the tubular portion of thestoker conduit, said upstanding walls being detachably sec'ured on theupper surface of said distributor head spaced inwardly at their loweredges from the side walls of said delivery portion and extendingupwardly to said side walls.

12. In combination with a stoker conduit having a tubular portionprovided with a bottom wall, the inner surface vthereof being arcuate intransverse cross section, and a delivery portion immediately forward ofsaid tubular portion, said delivery portion including upright sidewalls, ledges extending laterally inward of the lower ends of saidupright side walls and forward of the lower forward end of said tubularportion, a distributor head seated on said ledges between the lower endsof said side walls and immediately forward of the lower forward end ofsaid tubular portion, said distributor head including a fiat uppersurface constituting a support for coal passing through said conduit,and a separable 4 aieaoee arcuate upstanding wall located within and ateach side of said delivery portion immediately forward of the tubularportion of the 'stoker conduit, said arcuate wallsbeingdetachablysecured on the upper surface of said distributor v headspaced inwardly at their lwer edges from the side walls of said deliveryportion and curving upwardly and outwardly to said side walls.

13. In combination with a stoker conduit having a tubular portion'provided' with a bottom wall, the inner surface thereofl being arcuatein transverse cross section, and a delivery portion immediately forwardof said tubular portion, said delivery portion including' upright sidewalls, ledges extending laterally inward of 'the lower ends of saidupright side walls and forward of the lower forward 1 end of saidtubular portion, a distributor head seated on said ledges between thelower ends of said side walls and immediately forward of the lowerforward end of said tubular portion, said distributor head including afla-t upper surface constituting a support for coal passing through saidconduit, and an arcuate wall located within and ``at each side of saiddelivery portion immediately forward of the tubular portion of thestoker conduit, said arcuate walls beingintegrally formed with the uppersurface of said. distributor head spaced inwardly at their lower edgesfrom the side walls of said delivery portion and curving upwardly'andoutwardly to said side walls.

JOHN R.. GRAVES.

